Intermittent drive mechanism and a timer utilizing same



1968 s. F. MURRAY ETAL 3,417,631

INTERMITTENT DRIVE MECHANISM AND A TIMER UTILIZING SAME Filed June 23. 1966 2 Sheets-Sheet 1 INVENTORS STEPHEN F. MURRAY GEORGE A. HAMlLTON BY fig? ATTORNEY Dec. 24, 1968 s. F. MURRAY ETAL 3,417,631

INTERMITTENT DRIVE MECHANISM AND A TIMER UTILIZING SAME Filed June 23, 1966 2 Sheets-Sheet 2 Ill, Illlll INVENTORS STEPHEN F. MURRAY GEORGE A. HAMILTON ATTORNEY United States Patent 3,417,631 INTERMITTENT DRIVE MECHANISM AND A TIMER UTILIZING SAME Stephen F. Murray, Heather Hills, and George A. Hamilton, Indianapolis, Ind., assignors to P. R. Mallory & Co. Inc., Indianapolis, Ind., a corporation of Delaware Filed June 23, 1966, Ser. No. 559,917 12 Claims. (Cl. 74-125) ABSTRACT OF THE DISCLOSURE A spring biased dog means pivotally mounted on the free end of an arm pivotally mounted on a shaft, intermittently engages a drive means. Engagement of the dog means by the drive means causes an engaging means pivotally mounted on the dog means to drive a ratchet means mounted on the shaft.

The present invention relates to drives mechanisms and more particularly to the means and methods for providing a drive mechanism for intermittently advancing a shaft. The drive mechanism of the present invention is ideally suited for advancing the camshaft of a timer of the type including a plurality of cams mounted on a camshaft so as to be rotated thereby, and a plurality of switches arranged so as to be operated by the cams.

Intermittent drive mechanisms for advancing timers of the aforementioned type usually store energy in a spring and intermittently release the stored energy to advance the camshaft. This energy storing type of intermittent drive mechanism is usually referred to as an escapement mechanism. Another type of drive mechanism used on timers is referred to as a constant speed drive mechanism. The constant speed drive mechanism normally connects the camshaft directly to the drive motor so as to constantly advance the camshaft.

The intermittent drive mechanism of the type storing energy for intermittently advancing the camshaft is somewhat troublesome in timer applications because the various elements in the drive mechanism are constantly under load. Also, when the stored energy is released to advance the camshaft, considerable backlash of the ele ments in the drive mechanism is created. The constant loading of the elements and the backlash problem tends to wear out the elements.

The constant speed driving mechanism of the abovementioned type is somewhat of a problem in timer applications because the camshaft and cams are constantly rotated and, therefore the switches associated with the cams are slowly opened and closed. It is well known in the timer art that slow opening and closing of switches tends to burn up the switch contacts.

The drive mechanism of the present invention does not store energy in a spring nor does it constantly advance the camshaft. Thus, the drive mechanism of the present invention is a solution for the aforementioned problems. Other features of the drive mechanism of the present invention will become apparent as this specification progresses.

It is an object of the present invention, therefore, to provide an improved drive mechanism for intermittently advancing a shaft.

It is another object of the present invention to provide a drive mechanism for intermittently advancing a shaft without storing and subsequently releasing energy.

It is a further object of the present invention to provide an intermittent drive mechanism for advancing a shaft wherein there is a means for overriding the mechanism if the shaft can not be turned.

3,417,631 Patented Dec. 24, 1968 It is still another object of the present invention to provide an intermittent drive mechanism for advancing the camshaft of a timer wherein there are means for adjusting the position of the camshaft with respect to the drive mechanism.

It is yet another object of the present invention to provide a drive mechanism for advancing a shaft wherein the elements of said drive mechanism are unloaded throughout most of each revolution of the drive means associated with said mechanism.

The present invention, in another of its aspects, relates to novel features of the instrumentalities described herein for teaching the principal object of the invention and to the novel principles employed in the instrumentalities whether or not these features and principles may be used in the said object and/ or in the said field.

Other objects of the invention and the nature thereof will become apparent from the following description considered in connection with the accompanying figures of the drawing, and wherein like reference characters describe elements of similar function therein and wherein the scope of the invention is determined rather than the dependent claims.

For illustrative purposes the invention will be described in connection with the accompanying drawing in which:

FIGURE 1 is an exploded perspective view illustrating the addition of the intermittent drive mechanism of the present invention to a timer of the type having a plurality of cams mounted on a camshaft so as to be rotated thereby and a plurality of switches arranged so as to be operated by the cams.

FIGURE 2 is a fragmentary top view illustrating a means for providing a clock setting for a timer.

FIGURE 3 is a top view of the aforementioned timer showing the intermittent drive mechanism of the present invention at rest.

FIGURE 4 is a top view of the aforementioned timer showing the intermittent drive mechanism as it is actuated.

Generally speaking, the present invention is a drive mechanism for intermittently advancing a shaft. There is a substantially constant driving means and a gear means engaging with and driven by the drive means. The gear means carries at least one drive pin extending therefrom. There is an arm means pivotally mounted about a common axis with the driven shaft and extending towardthe gear means. Stop means are disposed on each side of the arm means so as to limit the travel thereof. There is a dog means pivotally mounted on an end of the arm adjacent to the gear means. The dog means has a first end with an extension thereon for engaging the aforementioned drive pin and a second end connected to the arm means by a first resilient means. There is a second resilient means for urging the arm means against a first of the aforementioned stop means. A ratchet means is operatively connected to the driven shaft. An engaging means for advancing the ratchet means when the arm means is pivoted against a second of the stop means by the drive pin, is connected to the arm means. The dog means is arranged so as to pivot against the first resilient means to disengage the drive pin when the arm means is against the second stop means.

Referring now to the drawing and particularly to the exploded perspective view of FIGURE 1, the structure of an illustrative embodiment of the present invention can be discussed.

As stated previously, the intermittent drive mechanism of the present invention is ideally suited for intermittently advancing the camshaft of a timer. Because of this, the illustrative embodiment of this specification will be an intermittent drive mechanism in a timer.

The timer, indicated generally by the reference number 10, is mounted on a base plate 11 fabricated of a suitable metal. The intermittent drive mechanism, indicated generally by the reference number 12, is arranged on the base plate 11 as shown in FIGURE 1. A substan tially constant speed motor 13 is mounted on the base plate 11 by screws 14 which thread in to the plate. The screws 14 also secure a member 15 to the base plate 11 by extending through holes 16 in the member 15. A pinion gear 13 on the output shaft of the motor 13 extends through a hole 17 in the member 15 to engage a driven gear 18. The driven gear 18 is rotatably mounted on the base plate 11.

A subinterval cam 19 is integrally formed on the top of the driven gear 18 and is arranged to operate subinterval switch 20 as the driven gear rotates. The subinterval switch 20 is staked to the member 15 at the points 20.

A drive pin 21 is integrally formed on the bottom of the driven gear 18 and is arranged to engage a linkage means, indicated generally by the reference number 22, adapted to operate a ratchet means comprised of a ratchet wheel 23, drive pawl 24 and backup pawl 25.

The linkage means 22 includes an arm 26 pivotally mounted about a bearing post extending through the base plate 11. The drive pawl 24 is pivotally mounted on the arm 26 and spring loaded so as to engage and drive the ratchet wheel 23 when the intermittent drive mechanism 12 is operated. The spring load for the drive pawl 24 is provided by a leaf portion 27 extending from said drive pawl and held by a tank 28 on the arm 26 so as to resiliently urge the drive pawl against the ratchet wheel 23. There is a dog 29 pivotally mounted on the end of the arm 26 adjacent to the driven gear 18. The dog 29 has an extension 20 on one end for cooperating with the pin 21 on the driven gear 18 and a notch 31 on the opposite end for receiving one end of a spring 32. The opposite end of the spring 32 is connected to a notch 33 on the arm 26 so as to bias the dog 29 against the force applied by the pin 21. There is a second spring 34 resiliently connecting the arm 26 to the base plate 11. In the illustrative embodiment, the spring 34 also biases the backup pawl against the ratchet wheel 23. The spring, therefore, is a resilient means for returning the arm 26 to its normal position after actuation by the driven gear 18.

There is a tang 35 struck out of the base plate 11 so as to provide a tang for the arm 26. The position of the tang 35 determines the amount of travel of the arm 26 and, consequently, of the ratchet wheel 23.

The ratchet wheel 23 is mounted on a boss 36 of a member 37 which is rotatably mounted on a base plate 11 about the same axis as the arm 26. The boss 36 has an axially located slotted hole 38 for receiving a double-D portion 39 of a camshaft 40. The member 37 has a radial extension 41 with a slotted hole 42 therein. A screw 43 extending through the slotted hole 43 threads into a hole 44 in the ratchet Wheel 23. The screw 43, slotted hole 42 and hole 44 provide a means for adjusting the ratchet wheel 23 with respect to the member 37, thereby providing a clock setting for the timer. A hole 51 is provided in the base plate 11 for loosening the screw 43 to adjust the ratchet wheel 23 with respect to the member 37.

A plurality of earns 45 are mounted on the camshaft 40 so as to be rotated thereby. An insulative sidewall 46 of the timer 10 has a plurality of control switches 47 mounted thereon. Another sidewall 48, not shown in FIGURE 1, has similar switches 47 mounted thereon. One of these switches 47 is operated at subintervals by a linkage 49 which cooperates with the subinterval cam 50 which is internal to the subinterval cam 19. The balances of the switches are operated by the cams 45.

Referring now to FIGURE 2, it can be seen that loosening of the screw 43 in the slot 42 will permit adjustment of the ratchet wheel 23 in the directions of the arrow 52 and with respect to the member 37.

Referring now to FIGURES 3 and 4 a top view showing the cooperation of the various elements of the intermittent drive mechanism when it is at rest and actuated and other elements not discussed in conjunction with FIG- URES l and 2 can be discussed.

A portion of the ratchet wheel 23 is shown cut away to illustrate .a tang 53 struck out of the base plate 11 so as to provide a back stop for the arm 26. Thus, the arm 26 can pivot through an are established by the positions of the tangs 35 and 53 which comprise first and second stop means for the arm.

The pinion gear 13' on the output shaft of the motor 13 is shown engaged with the driven gear 18 in FIGURE 3.

It can be seen that the dog 29 is pivoted on a post 54 on the end of the arm 26 and the extension 30 of the dog 29 extends under the driven gear 18 so as to interfere with rotation of the pin 21. Thus, as the gear 18 rotates in the direction of the arrow 55, the pin 21 will engage the extension 30 to pivot the arm 26 against the tang 35. Referring now to FIGURE 4, it can be seen that when the arm 26 is against the tang 35, the dog 29 has to pivot in the direction of the arrow 56 to permit passage of the pin 21 thereby.

With the above structural description in mind, and by making reference to the drawing figures, the following analysis of operation will serve to convey the functional details of the present invention.

The motor 13 drives the driven gear 18 at a substantially constant speed. The pin 21 on the driven gear 18 engages the extension 30 on the dog 29 one time for each revolution of the driven gear 18. By merely adding other pins, similar to the pin 21, the dog 29 can be actuated more than one time for each revolution of the driven gear 18.

Before the pin 21 engages the extension 30 on the dog 29, the intermittent drive mechanism 12 is in the condition shown in FIGURE 3. Specifically, the arm 26 is against the tang 53 and the dog 29 is held in its normal position by the spring 32. When the pin 21 initially engages the extension 30, the arm 26 is pivoted against the tang 35 and the pawl 24 advances the ratchet wheel 23. As the pin 21 rotates farther, the dog 29 is pivoted about the post 54 to permit passage of the pin. The spring 32 which holds the dog 29 in its normal position, therefore, is a means for determining the amount of torque applied to the ratchet wheel 23. Also, as a safety feature, if the camshaft is locked for some reason, the spring 32 will permit the dog 29 to pivot about the post 54, thereby permitting passage of the pin 21. Once the pin 21 has rotated past the extension 30 of the dog 29, the spring 34 will return the arm 26 to its normal position against the tang 53 as shown in FIGURE 3.

The ratchet wheel 23 is advanced one or more tooth spaces each time the arm 26 is pivoted between the tangs 35 and 53. The angular distance between the tangs 35 and 53, therefore, determines the amount of movement of the ratchet wheel 23.

From the description provided above it can be seen that the intermittent driven mechanism of the present invention is not an energy storing device as is the case with most contemporary intermittent driven mechanisms used in timers, nor is the mechanism a constant speed driving mechanism of the type that constantly rotates the camshaft. One advantage of the intermittent driven mechanism of the present invention is that the torque applied to the ratched wheel can be regulated by changing the characteristics of the spring 32 cooperating with the dog 29. Another advantage of the mechanism is that more than one pin can be used on the driven gear to actuate the dog 29. Still another advantage of the mechanism is that the amount of movement of the arm 26 can be changed by changing the angular distance between the tangs 35 and 52. For instance, it would be possible to have adjustable stops in lieu of the tangs 35 and 53 so as to vary the amount of travel of the arm 26 and, consequently, the ratchet wheel 23. Yet another advantage of the mechanism is that the motor 13, runs unloaded, with the exception of the subinterval switches, for most of each revolution. This feature saves wear and tear on the components.

The intermittent drive mechanism of the present invention, as hereinbefore described in one of its embodiments is merely illustrative and not exhaustive in scope. Since many widely different embodiments of the invention may be made without departing from the scope thereof, it is intended that all matter contained in the above description and shown in the accompanying drawing shall be interposed as illustrative and not in a limiting sense.

What is claimed is:

1. A drive mechanism for intermittently advancing a shaft comprising, substantially constant speed drive means, gear means engaged with and driven by said drive means, said gear means carrying at least one drive pin extending therefrom, arm means pivotally mounted about a common axis with said shaft and extending toward said gear means, stop means disposed on each side of said arm means so as to limit the travel thereof, dog means pivotally mounted on an end of said arm means adjacent to said gear means, said dog means having a first end terminating in an extension for engaging said drive pin and a second end connected to said arm means by a first resilient means, second resilient means for urging said arm means against .a first of said stop means, a ratchet wheel adjustably mounted on a bearing member on said shaft and pawl means pivotally mounted on said arm means and resiliently urged toward said ratchet wheel for advancing said ratchet means when said arm means is pivoted against a second of said stop means by said drive pin, thereby advancing said shaft, said engaging means being connected to said arm means, said dog means being arranged so as to pivot in opposition to said first resilient means to disengage said drive pin when said arm means is against said second stop means.

2. The drive mechanism according to claim 1, wherein said second resilient means is arranged so as to urge a backup powl into engagement with said ratchet Wheel.

3. The drive mechanism according to claim 1 wherein said first resilient means is adapted to permit pivoting of said dog means to disengage said drive pin when said shaft is prevented from rotating.

4. In a timer, a drive mechanism for intermittently advancing a shaft comprising drive means, biased arm means pivotally mounted on said shaft and extending toward said drive means, stop means limiting the angular displacement of said arm means, biased dog means movably mounted on said arm means and having an end thereof terminating in an extension engaging said drive means so as to pivot said arm means through said drive means, ratchet means operatively connected to said shaft, and biased engaging means movably mounted on said arm means engaging said ratchet means and causing said ratchet means to be advanced upon the engagement of said dog means with said drive means.

5. In a timer, a drive mechanism according to claim 4, wherein said dog means and said engaging means are pivotally mounted on the free end of said arm means.

6. In a timer, a drive mechanism according to claim 4, wherein said dog means and said engaging means are spring biased.

7. In a timer, a drive mechanism according to claim 4, wherein said drive means includes a gear means having at least one drive pin extending therefrom.

8. In a timer, a drive mechanism according to claim 4, wherein said stop means are tang means lanced on either side of said arm means from the base plate carrying said drive mechanism.

9. In a timer, a drive mechanism according to claim 6, wherein said arm means is spring biased through spring means connecting said arm to a backup paJwl whereby said backup pawl is urged into engagement with said ratchet means.

10. In a timer, a drive mechanism according to claim 6, wherein said dog means is spring biased through spring means connecting an end of said dog means to said arm means.

11. In a timer, a drive mechanism according to claim 4, wherein said ratchet means is a ratchet wheel adjustably mounted on a bearing member so as to provide .a means for adjusting the position of said shaft with respect to said drive means.

12. In a timer, a drive mechanism according to claim 4, wherein said drive means includes cam means cooperatively engaging subinterval switch means.

References Cited UNITED STATES PATENTS 966,977 8/1910 Zahn 74-125 FOREIGN PATENTS 931,461 8/ 1955 Germany.

FRED C. MATTERN, JR., Primary Examiner.

WESLEY S. RATLIFFE, Assistant Examiner. 

